Peritonsillar abscess (PTA) is one of the most common head and neck infections that is diagnosed in the emergency department. The common presenting symptoms are a muffled/altered voice, throat pain, fever and odynophagia. A non-contrast CT image of a particularly severe example of a PTA is shown below.

The next horizontal cut image is below, with red arrows to highlight the abscess.

One of the more striking aspects of the image is the large degree of airway compression, with the maximum measured diameter of the airway being 2cm. Also, the first image shows that the abscess has two distinct “pockets” that eventually coalesce.

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To backtrack, this particular patient initially presented with symptoms of fever, chills, dysphagia, dysphonia and trismus. On examination, there were thin tonsillar exudates, erythema and deviation of the uvula. A diagnosis of peritonsillar abscess was made without imaging and the patient underwent incision and drainage, given antibiotics and discharge. The above images were taken after the patient returned to the ED several days later with continued, worsening symptoms.

The options for imaging of a soft tissue infection of the head and neck include CT and ultrasound. In the ED setting, ultrasound is becoming more and more utilized as the preferred imaging modality. However, this patient received a CT because they failed therapy. CT is superior to ultrasound in differentiation between peritonsillar abscess and other infections of the oral cavity and pharynx. It also allows clinicians to determine the degree of airway compromise. Other indications for CT imaging in suspected peritonsillar abscess include: uncertain diagnosis, obstructed view through physical exam or suspicion of an associated infection such as peritonsillar cellulitis.

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Overall, peritonsillar abscess is one of the most common soft tissue infection of the head and neck that is encountered in the emergency department. Most of the time, the diagnosis is clinical. Ultrasound is the preferred imaging modality, but CT is useful in a variety of situations as well.

20 year old male presents with neck fullness and wheezing. Had the sensation of “fullness” for about a year, worsening significantly over the past week. Now he complains primarily of trouble swallowing and wheezing.

On exam the patient has a definite right sided neck mass, minimally mobile but unclear if associated with the thyroid. Lungs with a biphasic wheeze and sats low 90s. Positive Pemberton’s sign with facial plethora and JVD when he raised his arms above his head.Here is his neck CT with IV contrast:

The CT revealed a 4.9 x 4.2cm multi cystic mass occupying the right lobe of the thyroid with some tracheal compression. TSH <0.02. The patient was admitted and approximately 45ml of fluid was drained from his cystic lesion with significant improvement in his symptoms initially, although this fluid recurred over the subsequent month. He is currently being worked up for thyroid pathology and may undergo a hemithyroidectomy in the near future.

Of note, there is some controversy surrounding the use of iodinated contrast in patient’s with suspected thyroid masses. This iodine bolus may interfere with a subsequent radioiodine scan, and theoretically may delay a patient’s therapy with radioactive iodine, if ultimately indicated.

This person came in after a high speed motor vehicle collision. Their main complaint was neck pain near C-7:

As you can see under bone windows there is a fracture of C7. One could stop here and be satisfied that you see the primary pathology in which you were interested. However, anytime you look at a CT you should pay attention to all parts of the image. Secondary findings are very common, especially in trauma. When assessing a CT image, one should change windows on the image to adequately look at all types of tissue that are present. In a cervical spine CT, the top of the lungs are usually visualized in the catchment area as you get to the upper t-spine. If you change the window to “lung” windows this is what you’ll see:

This person also has an anterior, small pneumothorax! This could have easily been missed if not changing the window to look at the lungs.

One of the basics of CT imaging is to change windows for all types of tissue. In the head, your main window change will be from “brain” to “bone” to adequately visualize bony structures of the calavarium. In the abdomen you should switch to “lungs” to visualize the lungs as well as switch to “bone” to visualize the ribs, pelvis, and spine. There are many other examples of this principle, but we will leave it at this for now.

This image was sent to me by one of my colleagues. He saw an un-immunized 22-year-old with sore throat and muffled voice:

This CT shows swelling and edema in the epiglottis. CT imaging of this diagnosis can occur in the STABLE epiglottitis patient. It will likely be a patient with unclear pathology and identified on CT rather than a easily clinically identified epiglottitis. Why? Because clinical epiglottitis that is very clearly identified is an airway emergency and they don’t end up in the CT scanner. The classic appearance will be a patient in the “tripod” position, drooling, stridor, hoarse voice, and looking ill. Lateral soft-tissue plain films can also make the diagnosis. Usual suspects causing epiglottitis include: H. Influenza, S. Aureus, Streptococcus sp., and Moraxella Catarrhalis (1).

Epiglottitis affects both children and adults and should be on your differential in an adult with these symptoms. Since childhood vaccinations have become widespread in developed countries the incidence of childhood epiglottitis has decreased. The incidence has remained stable in adults. This patient is interesting because of the un-immunized status.

Some thoughts pertaining mainly to children:

CT imaging of the neck in children is a controversial subject. Remember that the thyroid gland is anatomically present in the radiation area and the future risk of thyroid malignancy isn’t quite known. You must weight the risk of radiation against the benefit of the imaging test in this situation. CT is very good at detecting and characterizing childhood illnesses such as peritonsillar abscess, retropharyngeal abscess, and epiglottitis. If you highly suspect one of these pathologies CT is usually warranted as these diagnoses can cause significant morbidity and will many times need intervention. Keep in mind, however, that soft tissue neck plain radiographs may give you enough information to direct management and has much less radiation burden.

Some radiology signs are applicable to epiglottitis:

1. Thumbprint sign: on lateral CT or Plain film the epiglottitis will resemble a thumb in shape and size rather than the expected thin appearance. This is present on the CT above.

2. Halloween sign: describes the usual appearance of the epiglottis on CT axial cut. See image on Wikipedia®. Halloween Sign.